The elephant shark genome project, initiated by scientists at the Institute of Molecular and Cell Biology (IMCB) to help in understanding the human genome, has received a major boost from a leading funding agency in the United States. The National Human Genome Research Institute (NHGRI), part of the US National Institutes of Health (NIH) which is the world’s foremost center for the support of biomedical research, has approved funds for sequencing the whole genome of the elephant shark. The estimated cost of the project is about US$5 million.
Through the efforts of a major international consortium, the sequence of the human genome was completely sequenced in 2003. However, identifying all the genes and other functional elements in the human genome has proved to be a major challenge. Comparison between the genomes of human and other animals is an effective approach for identifying functional elements in the human genome.
To facilitate such comparisons, genomes of ‘model’ animals such as chimpanzee, mouse, chicken, pufferfish and zebrafish have been sequenced by various groups. Two years ago, the IMCB scientists proposed the elephant shark as a ‘model’ genome because of its relatively small genome size1. Subsequently, based on sequences generated in a pilot project, they demonstrated that the human genome is more similar to the elephant shark genome than to pufferfish and zebrafish genomes2,3. These findings were surprising given that humans are evolutionarily more closely related to fishes than to the elephant shark, and further highlighted the importance of the elephant shark as a model for understanding the human genome.
The elephant shark, found only in the continental shelf off Southern Australia and New Zealand, belongs to the oldest group of living jawed vertebrates, known as ‘cartilaginous fishes’. By virtue of its evolutionary position, the elephant shark serves as a valuable reference genome for understanding the origins and evolution of human and other vertebrate genomes.
1Venkatesh, B., Tay, A., Dandona, N., Patil, J.G. and Brenner, S. A compact cartilaginous fish model genome. Curr. Biol. (2005) 15, R82-R83.
2Venkatesh, B., Kirkness, E.F., Loh, Y.H., Halpern, A.L., Lee, A.P., Johnson, J., Dandona, N., Viswanathan, L.D., Tay, A., Venter, J.C., Strausberg, R.L. and Brenner, S. Ancient noncoding elements conserved in the human genome. Science (2006) 314, 1892.
3Venkatesh, B., Kirkness, E.F., Loh, Y.H., Halpern, A.L., Lee, A.P., Johnson, J., Dandona, N., Viswanathan, L.D., Tay, A., Venter, J.C., Strausberg, R.L. and Brenner, S. Survey sequencing and comparative analysis of the elephant shark (Callorhinchus milii) genome. PLoS Biol. (2007) 5(4): e101.
Click here for the Elephant Shark Genome Project webpage: